Eaphael josia



NITED STATES ATENT FFICE.

RAPHAEL JOSIA, OF FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES 0F LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,505, dated October 3, 1882.

Application filed August 9, 1882.

cess of treating or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles of a material which Ihave termed certaldite without pulverization of the gypsum..

In said application I described briefly certain of the compounds or compositions which I employ to produce certain efi'ects and the manner of using them, but stated that separate applications would be made for patents for such compositions.

The present application iclates to one of the compositions so referred to, and it is designed for use in the process herein described in the making of ed certaldite.

In carrying out the process referred to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such, by the use of suitable well-known tools. The gypsumemployed may be the ordinary native gypsum of commerce, though I prefer that which is comparatively pure or free from other matters of different composition. Such gypsum is usually obtained hydrated, or containing a certain percentage of waterin its composition; and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the whole of such water. ing it to the action of a gradually-increasing heat, Varying by preference with the size and quality of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration is obtained. The length of time as well as the degree of heat required to effect this result will vary somewhat with the size, character, and purity of the gypsum employed; but the temperature should not exceed 500 Fahrenheit, and both it and the time of exposure This is done by subject-- (No specimens.)

should be regulated and limited with reference to securing uniformity of treatment throughout the Whole mass or body. This operation may be known to be complete when a fracture of a test block presents a uniform white color. Any suitable drying or baking apparatus may ing known in kindred branches of the arts; but it should be of such construction that the material under treatment shall not be brought into direct contact with the fire. When the desired dehydration has been effected the furnace is allowed to cool gradually, in order that the material under treatment may be cooled gradually; or thematerial may be removed with due care to prevent breaking and exposure to nace gradually until it is reduced in temperature sufficiently to permit handling with safety in its subsequent treatment, which is designed to impart to it the desired color or tint and a high degree of insolubility and hardness throughout its mass. This step involves the use of the composition which forms the subject-matter 0t inventionv in the present application. This composition is formed of the following elements: water, by weight, two hunoxalic acid, by weight, two to two and a half parts; Brazil wood, by weight, six parts; chloride of zinc, by weight, one part; cream-tartar, by weight, twotenths part. These ingredients, being. mixed in about the proportions named,form a solution which is used as a bath, and to this end a suitable quantity of it is placed in a vessel of proper shape to receive the article to be treated, which is dipped or immersed in the bath and subjected to its action until the article has acquired the desired degree of hardness and color. The length of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or solution, the porosity and nature or physical and chemical condition of the article; but usually twelve hours (more or less) will snlfice, though to secure uniformity of treatmentand ol' resultthrough the whole body or mass of the article I prefer repeated dippingstwo, three, or moresay two or three seconds at first, and increasing gradually to be employed for this purpose, many such bedred parts; alum, by weigh t, four to five parts;

moisture, and allowed to cool outside the furone, two, or three or more. minutes, more or less, with drying intervals of like increasing length between clippings, for halfor threequarters of an hour or so, after which the article may remain in the bath for twelve hours or so.

Vhile I do not limit my invention by any particular theory of chemical or physical reactions involved in the use of this bath as above described, I believe, with my present knowledge, that the salt (alum) held in solution, by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the calcic sulphate and renders it more compact, harder, and less soluble, and that the oxalic acid of the bath acts chemically or physically upon the impurities or matters of other composition, (carbonates, &c.,) which are usually contained in greater or less quantities in native gypsums, and produces a like indurating efi'ect upon them, though the salt may also have an indurating action upon the impurities present, and the acid may act in like manner more or less upon the calcic sulphate. The Brazil wood and cream-tartar of the bath give the desired red color and the chloride of zinc acts as a mordant. This color will usually be variegated somewhat by lines, veins, or markings of darker shades, due probably to impurities present in the oa-lcic sulphate, giving the article a beautiful and highly-ornamental appearance. A degree of hardness,compactness, a-nd insolubility is also secured by this treat- 'ment, as well as beauty of color, which renders the article an excellent and valuable substitnte for marbles, ornamental stones, tiles, &c., and other materials of kindred nature in the various uses to which they are applied in the arts.

\Vhen the article has been treated in the bath as above described it is removed and dried by exposure to the sun or to an equivalent furnace-heat for one or two hours, or by ordinary atmospheric exposurefor two or three days, when it is ready for polishing and such other manipulation as may best tit it for itsintended use, which may be done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications of the same, as circumstances may require, forms the subject-matter of the first application herein referred to. Neither do I limit my presentinvention to the particular way herein described of applying it, though I now believe'this way or process to be the best. I also believe the proportions of ingredients which I have named in forming my improy'ed composition to be the best for the purposes stated, and, among oth ers, to secure a uniform degree of hardness and color throughout the mass of the article. If the solution be very strong, there is great dam ger of rendering the surface of the article hard very quickly, and thereby preventing proper action of the bath upon the interior substance of the article; or if the solution be very weak too much time is required, and even then a proper degree of hardness, density,and insolubility is not secured; also, by the conjoint action of all the elements of the bath much better results are secured, especially upon native gypsums, than by a solution formed of a part of the elements. For these reasons I prefer to employ all the elements of the compositions in substantially the proportions named; but such limits, though affording the best results, may be varied or exceeded somewhat and still obtain favorable results under skillful manipulation, and all such modifications employing the elements substantially as herein described and in about the proportions set forth I consider as coming within my invention and claim.

I claim as my invention-- The composition herein described for treating dehydrated gypsum, consisting substantially of the following elements: water, alum, oxalic acid, Brazil wood, chloride ot'zinc, and crea|n-tartar,i n about the proportions setforth.

In testimony whereofI have hereunto set my hand.

RA PIIAEL JOSIA.

Witnesses:

Gnlno PAN'IALIONY, B. H. WHITTLESEY. 

